This invention relates to programs that share data across disparate computer applications and platforms, such as handheld computers and desktop computers.
Handheld computers typically weigh less than a pound and fit in a pocket. Handheld computers typically provide some combination of personal information management functions, database functions, word processing functions, and spreadsheet functions. Owing to the physical and memory size, and processing power limitations of the handheld computers, however, these applications are generally limited in functionality and differ in data content and usage from similar applications on desktop computers.
Many users of handheld computers also own a desktop computer used for applications that manage data similar to the data carried in the handheld computer. In such cases, the user normally would want the same data on the desktop computer as in the handheld computer. There are a number of programs that transfer data between handheld computers and desktop computers, but they all create desktop computer's data with no regard for prior contents. As a result, all updates that have been done to the desktop computer's data prior to the transfer are ignored.
Many desktop computer applications have their data stored in large, complex, proprietary formats. Data transfer to these applications usually cannot take place through file transfer, because the data comes from the handheld computer in a different format and usually is a subset of the data held on the desktop computer. In such cases, data can only be communicated to and from the desktop application by the use of a database manager or by use of dynamic inter-application communication techniques.
Many handheld and desktop programs work with database files. Database files have a file format, the set of rules by which data can be read from or written to the file. A database file is composed of records, some of which are data records with the data of interest to the application program and the user, and often some header records. Each data record is composed of fields, and each field has a name and a data format. Examples of data formats include 1-, 2-, and 4-byte integers, a 4-byte or 8-byte floating point number, or one or more ASCII text strings. In the case of multiple text strings in one field, the strings (or subfields) are separated by a special character such as tab or linefeed. Each data record of a file shares the same record structure: a record structure is described by the fields' names, data formats, and byte offsets in the record. The file format's rules include a description of the record structure of the constituent data records, the record structure for any header records and how these header records aid navigation to find specific data records and/or specific fields within those records, "hidden" key tags to help find a record, and any rules that application programs use to access a particular record and field.
Database files are managed by two broad classes of programs, database managers and other application programs. A database manager is a program for managing general databases, that is, database files whose record structure can be specified at creation time by the user. Database manager programs maintain data dictionary records as headers in the database file. These data dictionary records specify each field's name, start byte offset within the record, and data format. Examples of database manager programs include Paradox, dbase, and IBM Current.
Other database files are managed by special-purpose application programs. These programs work on databases of one specified record structure; this specification is embedded in the code of the program rather than in header records of the file. For instance, a telephone directory program may work on files with a 32-character name and a 10-character phone number. This record structure would have been encoded in a data structure declaration in the source of the program.
One or more of the fields of a database record structure are designated as the key, the "name" by which the record can be specified for reading or writing. Some database files, typically those for schedule application programs, have "range keys"--the key specifies start and end points in a 1-dimensional key space rather than a single point in the (possibly multi-dimensional) key space. Range keys may specify multiple intervals, for instance "9AM to 10AM every Monday until Nov. 17." Where non-range keys must be unique--there cannot be two records with the same non-range key--range keys may overlap or even be exactly equal, though typically these are undesirable situations and should brought to the attention of the user.
Because handheld computers of the current generation are diskless, "files" in the classical sense do not exist on many of these handheld computers. Within this patent, the term file should be understood to include the memory-resident datasets of a handheld computer, and the serial bit stream format in which a handheld computer sends or receives data to/from another computer.
File copying and data conversion are long-standing problems in the art, and many solutions to different parts of the problem have been offered.
U.S. Pat. No. 4,966,809 describes a technique for sharing data among disparate platforms with differing data formats, but leaves unsolved the problems of sharing data among platforms that require different record structures or file formats (broader problems that include the data format problem as a constituent), and does not provide a method for a user of these disparate platforms to conveniently instruct his system about his environment so that the system will apply itself in that environment.
There are several file transfer programs for communicating between computers, including Organizer Link 2 from Sharp.RTM. Electronics, PC-Link for the Casio B.O.S.S..TM. from Traveling Software.RTM., HP95LX Connectivity Pack from Hewlett Packard, and 3 Link from Psion PLC. These file transfer programs do not provide the invention's user-specifiable field mapping of data nor dynamic reconciliation of data.